Section 9- Oceans Flashcards
(25 cards)
Equation for enthalpy change of solution?
Enthalpy change of hydration for Cation I.e. Na+(ΔHhyd) + Enthalpy change of hydration for Anion I.e. Cl-(ΔHhyd) - Enthalpy change of lattice enthalpy ΔLEH
What type of solvents are there?
Polar
Non polar
What allows something to dissolve?
If the ion-dipole charges formed between the molecule and the solvent are greater than the forces holding the molecule together.
What is standard lattice enthalpy?
The energy released when one mole of a lattice is formed from its gaseous ions under standard conditions.
When water surrounds ions dissolving them, the ions are known as what?
If any solvent other than water dissolves the ions, what is the process called?
Hydrated ions, the process is hydration.
Solvation
What is the standard lattice enthalpy?
The enthalpy change when one mole of a lattice is formed from is gaseous ions under standard conditions.
What is the enthalpy change of hydration?
The enthalpy change when one mole of aqueous ions are formed from their gaseous counterparts.
What is the enthalpy change of solution?
The overall enthalpy change when one mole of ionic substance dissolves in enough solvent to form and infinitely dilute solution.
How does charge density affect:
Enthalpy change of lattice enthalpy
Enthalpy change of hydration
More exothermic. The ions are attracted to each other more, and the bonds formed to make the lattice release more energy.
More exothermic. Water is attracted to the ions more. So the ion-dipole bonds are stronger and release more energy upon formation.
What is the equation for the total entropy change?
totS = sysS + surrS
What is sysS?
Sproducts - Sreactants
What is surrS?
-(change in temp in kJ)/T(in Kelvin)
How do you show if a reaction is feasible?
totS is either 0 (in equilibrium) or bigger than 0.
Rule about enthalpy change of solution and what information it gives respective to solubility
If the enthalpy change of solution is less than 50 kJmol^-1 the substance will tend to dissolve. If it’s above 50kJmol^-1 it will tend not to.
What are bronsted-Lowry:
Acids
Bases
Species which donate hydrogen ions
Species which accept hydrogen ions
When is the only time an equilibrium with conjugate pairs set up?
When a base dissolves in water
What is a conjugate acid base pair?
When on species acts as an acid in one reaction direction, and a base in another reaction direction.
What are the concentrations of H+ and OH- ions neutral solutions?
They’re equal to each other
pH= ?
-log[H+]
How could you find the concentration of an Acid or Base with on and not the other?
Titration
What is Kw?
Waters dissociation constant. 1x10^-14
Kw = [H+][OH-]
Kw = [H3O+][H+]
What is Ka used for?
What is the equation?
What assumptions?
Working out stuff with Weak Acids
Ka = [H+][A-]/[HA]
Ka = [H+]^2 /[HA]
The concentration of the weak acid is the same as it was at the start. The concentration of dissociates H+ ion and acid anion is the same, hence why it can be rewritten.
Anything like pH, has a p. What is the p?
-log10
What’s the definition of a buffer?
What are they typically made of?
A buffer is a solution that resists change in pH when small amounts of acid or base are added.
A weak acid/base and their salt
